Tuyere for cupola furnaces



July 12, R GERlScH TUYFJRE FOR CUPOLA FURNACES Filed July 8, 1931 Inventor H. ezzbcx Attorney.

Patented July 12, 1932 PATENT OFFICE RICHARD GERISCI-I, OF DUSSELDORF, GERMANY TUYERE non oUroLA FURNACES Application filed July 8, 1931, Serial No.

Tuyeres blowing alternately are known for preventing slagging in cupola furnaces as a result of short stoppages. These known constructions of tuyere have Various disadvantages: they cannot be always maintained effectively closed, as the closure members are too much exposed to the heat of the furnace and therefore oxidize and become distorted; they do not provide for the regulation of the tuyeres independently; the parts situated in the brickwork burn when the furnace lining melts, and collapse, thus leading to irregular distribution of the blast and to expensive repairs; the brickwork must be broken down, to replace damaged tuyeres; the interior of the furnace cannot be inspected when the tuyeres are closed, as long flames issue through the peephole when the door is opened, which are liable to cause injury to the operator from burns; during stoppages, carbon monoxide frequently collects both in the pipes connected with the tuyeres, as well as in the blast mains, and this gas, on restarting becomes mixed with air and may explode and cause damage.

The invention provides a tuyere for alternate operation which can be readily fitted and changed, even in old cupola furnaces, and is suitable for all types of furnace.

A construction of tuyere according to the invention is diagrammatically illustrated, by way of example, in the accompanying drawmg.

Figure 1 is a sectional side elevation of the tuyere according to the invention.

Figure 2 is a front elevation, partly in section, of the peephole closure device provided on the tuyere.

Figure 3 is a sectional rear elevation of a modification of the closure device for the peephole.

The tuyere consists of a body a of angular form, which is mounted so as to produce a horizontal or nearlyhorizontal blast thebody a is secured by means of bolts a to the outside of the blast main 7) so as to be readily detachable and in a position sheltered from heat or gases, is surmounted by the air-cooled closure member I), which is operated by the handle 0. The peephole c, with coverplate f, is disposed 549,403, and in Germany July 23, 1930.

opposite the air passage, below the closure member. The member 03 is situated in front of the tuyere.

According to the invention the tuyere is inserted already assembled in the furnace and can be quickly replaced as a unit. The peephole e disposed below the closure member 6 (in the direction of flow of the blast) enables the progress of the reaction in the furnace to be watched, even during a stoppage.

According to the invention the danger of flames issuing, when the cover f is moved to open the peephole, is prevented by interlocking the closure member I; of the tuyere with the peephole cover f in such a manner that, when the tuyere is closed the peephole cover cannot be opened, and when the peephole e is open the tuyere cannot be completely closed, so that an adequate blast can enter the tuyere to balance the back pressure from the furnace, despite the escape of air through the open peephole.

Figure 2 illustrates a construction of safety device according to the invention. The damper b is provided with a downwardly projecting stop 2' which advantageously serves to limit the inward movement of the damper. The cover 7 of the peephole e is mounted upon the pivot pin 9 and is adapted to be partially rotated about the pivot pin to uncover the peephole. The direction of rotation is determined by a stop 0 of any suitable form provided upon the front plate of the tuyere and serving to engage the handle q. The cover 7 is further provided at the upper end and towards the side which rises on the rotation of the cover with a lug h the outer edge or surface of which is formed to the arc of a circle struck from the pivot pin 9 such that when the damper b is in the open position and the cover 7 is rotated to uncover the peephole the lug h clears the under surface of the damper but obstructs the path of the stop 2' if the attempt be made to close the damper, so that the damper must remain open to a determined degree so long as the peephole is open. In order to permit the damper to be closed when the cover f is in the closed position, the stop 2' is formed with a recess 2' of a shape corresponding to the obstructing portion of the lug h which is received into such recess. Thus, the damper Z) being closed, the peephole cannot be opened as movement of the cover f is then obstructed by the contacting of the lug h with the opposed portion of the stop. According to Figure 1, the tuyere body a is mounted transversely to the blast main p in such manner as to be protected from the heat and to be cooled by the blast air, means are provided for limiting the travel of the closure member or damper Z) for opening the blast meet for the tuyere. For this purpose the closure member or damper Z) is provided with a projection and the tuyere body a, withan adjustable stop comprising a set screw with which the projection b may contact. \Vhen the closure member or damper Z) is-opened, the projection encounters the stop 70 and thus the blast inlet is limited according to the adjustment of the set screw.

' The invention provides the following advantages:

Each separate tuyere can be adjusted during operation to the optimum volume of blast air by regulation of the blast inlet, without which the tuyeres receive different volumes of blast air, according to their position in relation to the source of the air supply; the variation in the maximum opening of the closure member 6 is directly proportional to the adjustment of the set screw; different, exactly determinable volumes of blast air can be supplied in the case of difierent kinds of pig-iron and coke charges and the air can be correctly distributed; continuously increasing volumes of blast air can be admitted, during operation, to the cupola furnace whose diameter increases as its lining is burnt out.

According to the invention the tuyere body a has fitted in front of it a nozzle member d, fixed in the masonry. The upper surface of the bore of the member (Z is downwardly inclined towards the interior of the furnace, in order that a whirling movement may be imparted to the fire gases. This feature of the invention has the following advantages:

(a) The shape of the member cl creates eddies in the blast air which accelerate the combustion of the coke and prevent the formation of pin flames. The blast is directed horizontally in the tuyere body a and is then constricted by the sloping upper part of the member d. The horizontal downwardly acting stream of blast air, together with the expansion in the furnace and the sharp upward turn of the blast jet, produce an effective intermingling of the gases and an intensive combustion of the coke.

(b) The member all when worn can be removed and another substituted without breaking down the masonry.

(0) The more or less conical shape of the member cl in conjunction with the device for regulating the inlet, enables the use of the same interchangeable tuyeres for furnaces of different sizes.

According to the invention the peephole cover may be provided with means of protection for the peephole glass from heat, flames and vapours, by providing a slide which covers the glass and is pushed aside only during inspection. Figure 3 shows one form of construction of this device. The cover f is provided with a recess Z, housing a slide m, which can be moved across the glass by means of handle a, and thus protect it.

As each tuyere can be actuated and regulated independently of the others, two adj acent tuyeres can be shut off simultaneously, as is often necessary when melting down heavy lumps of scrap. The new tuyere has no levers or stuffing boxes.

I claim:

1. An interchangeable tuyere for cupola furnaces having a body formed to a right angle and set to produce a horizontal blast and provided with a peephole in the line of the blast, a closure member for said body and a peephole cover, the closure member and peephole cover being interlocked in such manner that the peephole cover cannot be moved to the open position when the closure member is in the closed position and the closure member cannot be moved completely into the closed position when the peephole cover is in the open position.

2. An interchangeable'tuyere according to claim 1, comprising a closure member guided on a horizontal upper surface of the tuyere body, a projection upon said closure member, and a stop, the position of which can be adjusted during the operation of the tuyere, the stop determining the length of travel of the closure member by engagement with the said projection.

3. An interchangeable tuyere according to claim 1, wherein the tuyere body is secured to the blast main from the outside by means which permit ready detachment.

4. An interchangeable tuyere according to claim 1, having a nozzle member disposed at the forward end of the tuyere body in the furnace wall.

5. An interchangeable tuyere according to claim 1, having a peephole cover provided with a glazed sight aperture and a slide adapted to cover the glazed sight aperture.

RICHARD GERISCH. 

